<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body{
            margin: 0;
        }
        .main{
            height: 100vh;
            background-color: pink;
            display: flex;
        }
        .box:nth-child(1){
            width: 200px;
            background-color: gold;
        }

        .box:nth-child(2){
            flex-grow: 1;
        }
        .box:nth-child(3){
            width: 400px;
            background-color: skyblue;
        }
    </style>
</head>
<body>
    <div class="main">
        <div class="box">1</div>
        <div class="box">2</div>
        <div class="box">3</div>
    </div>
</body>
</html>
